Relationship between Late Spring Soil Nitrate Concentrations and Corn Yields in New York

Abstract

Proper N management is important to optimizing profit and minimizing N loss. The efficiency of N use may be improved in humid regions with a reliable soil test to guide fertilizer N recommendations. Recently, a presidedress nitrate soil test (PSNT) has shown promise as a means of quantifying the size of the potential mineralizable organic N pool in soil. This study was conducted to determine if the PSNT could be used for corn (Zea mays L.) production to identify N responsive and non‐responsive sites, predict the economic optimum fertilizer N rate, and improve the current fertilizer N recommendation procedure. The PSNT gave a useful and defined critical level of 21 ppm nitrate‐N, delineating N responsive from nonresponsive sites. The success rate for making the correct decision about N responsiveness was 84%, indicating a good relationship between the PSNT and the ability of the soil to supply N. The PSNT was less precise in determining the economic optimum fertilizer N requirement (R1 = 0.50) for sites below the critical level. This probably was due to the inability of the PSNT to quantify organic N mineralization. The standard N recommendation, based on estimates of N availability from organic sources, was a slightly better predictor of the fertilizer N requirement (R2 = 0.67) than the PSNT. There is a need to further improve the methodology used for formulating fertilizer N recommendations. Research Question Proper N management is important to optimizing profit and minimizing N loss. The efficiency of N use may be improved in humid regions with a reliable soil test to guide fertilizer N recommendations. This study was conducted to determine if a presidedress nitrate soil test (PSNT) for corn could be used to identify N responsive and nonresponsive fields, predict the economic optimum fertilizer N rate, and improve the current fertilizer N recommendation procedure. Literature Summary Traditional fertilizer N recommendations are based on N credits from soil organic matter, crop residues, animal manures, and residual N carryover. The precision of the fertilizer recommendation is often variable owing to the difficulty in estimating N mineralization rates and N losses. Recently, a PSNT procedure was developed to measure the amount of soil nitrate in the surface 12 in. of soil when the corn is 6 to 12 in. tall. The PSNT has shown to be reasonably well correlated with the ability of the soil to supply N. Improvements in the fertilizer N recommendation through the use of the PSNT seem apparent. Study Description The study was conducted at 78 locations across New York from 1986 through 1991. Locations were selected to typify crop rotational sequences and N management practices. Multiple rates of fertilizer N were applied at 29 of the locations for the purpose of calculating economic optimum fertilizer N rates. The PSNT was correlated with relative yield at all sites. The relationship between the economic optimum fertilizer N rate, PSNT value, and the standard fertilizer N recommendation was compared. Applied Questions W...

Use of a pre-sidedress soil nitrate test (PSNT) to determine nitrogen fertilizer requirements for irrigated corn

“…In similar conditions, but for lower yield expectations (yield goal of 10 t grain·ha -1 ), Villar et al [25] found that a PSNT 0-30 cm level between 94 and 142 kg N·ha -1 (21 to 32 mg NO 3 -N·kg -1 ) was required. These values are also in concordance with the PSNT 0-30 cm levels found by other researchers [10,16,27]. The results from site P-2 suggest that, after alfalfa, corn does not need supplemental N fertilizer applications in this region, regardless of the soil nitrate levels found at sidedressing.…”

Relating Turfgrass Growth and Quality to Frequently Measured Soil Nitrate

“…Although the goal in amenity turfgrass is not to maximize the yield, similar critical values between turf-type and forage-type grass yields suggest that the maximum growth response of perennial cool-season grasses, whether for forage or turfgrass use in our climate, will be reached at soil NO 3 -N concentrations approaching 10 to 15 mg kg . The crops that have been studied include silage corn (Magdoff et al, 1990;Fox et al, 1989;Meisinger et al, 1992;Klausner et al, 1993;Sims et al, 1995), field pumpkin (Cucurbita pepo L.) (Morris et al, 2000), sweet corn [Zea mays subsp. saccharata (Sturtev.)…”

Opportunities for improved fertilizer nitrogen management in production of arable crops in eastern Canada: A review

“…Soil nitrate concentration at this time reflects carry-over of residual nitrate from the previous growing season, much of the additional soil mineral N resulting from spring applied manure (Zebarth and Paul 1997) and as much as 60% of the apparent growing season soil N mineralization (Zebarth et al 2001). The PSNT can be used to predict the sidedress rate of mineral fertilizer (Zebarth et al 2001) or liquid manure (Ball-Coelho et al 2005); however, the PSNT is generally more effective in identifying fields that will be responsive to sidedress N application than in predicting the optimal fertilizer N rate to apply at sidedress (Klausner et al 1993). In some cases, PSNTbased recommendations are adjusted for heavily manured fields (Jemison and Lytle 1996) or fields that have been under wet spring conditions (Scharf 2001).…”